Lipid soluble molecules bound to planar fluorescent dyes are useful as molecular reporters of their local environment (see Vincent et al., Biochem. Biophys. Res. Comm. 107, 914 (1982); Vincent et al., Biochemistry 21, 708 (1982); Slepushkin et al., Eur. J. Biochem. 173, 599 (1988); Molotkovsky et al., Chem. Phys. Lipids 58, 199 (1991); Gromova et al. Chem. Phys. Lipids 60, 235 (1992)). After introduction of these molecules into surfactant-containing matrices including but not limited to phospholipid bilayers, planar bilayers, or bulk solutions, polarized fluorescence spectroscopy may be employed to estimate the rotational motions or the fluorescent moiety, which in turn reflects the physical state of the organization of the matrix surrounding the fluorescent dye A major limitation of the usefulness of these fluorescent probes is their relatively short fluorescence lifetime. As a result, the interpretation of the dye rotational motions are complex due to detection of both in-plane and out-of-plane rotational motions (see Vincent et al., BBRC 107; 914 (1982); Vincent et al., Biochemistry 21; 708 (1982)). The probes comprising the present invention overcome this disadvantage. Due to their long fluorescent lifetimes, the rapid in-plane motions of the coronene probes are virtually not detected. This results in simplified interpretation of the polarized fluorescence data, and allows detection of events occurring on the submicrosecond timescale, which were previously undetectable using polarized fluorescence spectroscopy. Until the present invention, dynamics on the submicrosecond timescale have not been extensively investigated because of the lack of a suitable probe.
The rates of rotation on this extended timescale, previously undetectable by the use of polarized fluorescence spectroscopy, reflect important information about the local environment surrounding the molecular probe which is not obtainable by presently available fluorescence probes. The probes of the invention widen the window of investigation possible to allow study of these longer-lived phenomena, which include rotation rates of large proteins and molecular complexes from which hydrodynamic properties including shape and axial ratios can be estimated.